1. Field of the Invention
The present invention relates to a liquid ejection head that ejects liquid and to a method of manufacturing the liquid ejection head.
2. Description of the Related Art
Liquid ejection recording apparatuses perform recording by ejecting liquid onto recording media, such as paper, and have the following characteristics: high-speed recording, ability to record on various recording media, little mechanical noise during recording, low running cost, etc. FIG. 6A is an exploded sectional view showing components of a conventional liquid ejection head. FIG. 6B is a perspective view of the components shown in FIG. 6A. The conventional liquid ejection head includes recording element substrates 100 and 200, an element-substrate support member 300, a wiring substrate 400, and a wiring-substrate support member 500. The recording element substrates 100 and 200 are bonded to a flat surface of the element-substrate support member 300 with an adhesive 610. The recording element substrates 100 and 200 are electrically connected to the wiring substrate 400. The wiring substrate 400 is bonded to the wiring-substrate support member 500 with an adhesive 630. The wiring-substrate support member 500 is bonded to the element-substrate support member 300 with an adhesive 620.
In Japanese Unexamined Patent Application Publication No. 2002-19119, a thermosetting adhesive is used as the above-described adhesives. When the thermosetting adhesive is cured by heating in an oven, the recording element substrates 100 and 200 and the wiring-substrate support member 500 are bonded to the element-substrate support member 300, and the wiring substrate 400 is bonded to the wiring-substrate support member 500.
Furthermore, Japanese Unexamined Patent Application Publication No. 2007-55071 discloses that a light-curable adhesive is used to bond the recording element substrate and the element-substrate support member. In the technique disclosed in Japanese Unexamined Patent Application Publication No. 2007-55071, the light-curable adhesive is applied to four corners of a bonding surface of the recording element substrate and is irradiated with light (ultraviolet). Thus, the recording element substrate is bonded to the element-substrate support member.
In the conventional liquid ejection head as shown in FIG. 6, typically, the recording element substrates are made of silicon, and the element-substrate support member is made of resin. Thus, the coefficient of linear expansion of the recording element substrates is smaller than that of the element-substrate support member. Hence, if heat treatment is performed to bond the recording element substrates and the element-substrate support member with the thermosetting adhesive, as in Japanese Unexamined Patent Application Publication No. 2002-19119, a tensile stress due to the difference in coefficient of linear expansion therebetween is generated in the recording element substrates. Furthermore, after the heat treatment, a compressive stress due to cooling of the recording element substrates and the element-substrate support member is generated in the recording element substrates. As a result, deformation and displacement of the recording element substrates due to these stresses may occur. In contrast, if the recording element substrates and the element-substrate support member are bonded together with a light-curable adhesive, as disclosed in Japanese Unexamined Patent Application Publication No. 2007-55071, an increase in temperature of the recording element substrates and the element-substrate support member can be suppressed compared with the case where a thermosetting adhesive is used, and hence, deformation and displacement of the recording element substrates are reduced. However, further reductions in deformation and displacement of the recording element substrates are required, as will be described below.
In recent years, liquid ejection recording apparatuses are required to perform recording at higher speeds. High-speed recording may be achieved by two-way printing, in which a liquid ejection head ejects liquid both while moving from one end to the other end and while moving from the other end to one end as it reciprocates. However, two-way printing requires higher liquid-landing precision than one-way printing. In one-way printing, because there is one printing direction, displacement of the liquid-landing position may be corrected to some extent by printing correction. However, in two-way printing, if displacement of the liquid-landing position occurs in each of the two directions, correction of such displacement is relatively difficult. Thus, further reductions in deformation and displacement of the recording element substrates are required. Because temperature rise occurs also when a light-curable adhesive is applied to the flat surface of the element-substrate support member and the recording element substrates are bonded thereto, deformation and displacement of the recording element substrates due to the stress caused by thermal expansion remain.